AC - Outside unit humming, warm air through vents, 6 year old house

Old 09-03-10, 05:11 AM
Thread Starter
Join Date: Sep 2010
Location: usa
Posts: 1
Upvotes: 0
Received 0 Upvotes on 0 Posts
AC - Outside unit humming, warm air through vents, 6 year old house

Hi all. I'm new here.

So yesterday I came home from work to a baking hot house. Thermostat was set to 69, but displaying 78 for room temp.

I started doing some digging online for some simple diagnosis info. So far, I'm thinking I have a bad capacitor.

-Warm air coming out of vents
-Outside condenser fan is not spinning, but making a humming noise at times. (I have actually seen it start up randomly, but only for a couple minutes before it shuts off completely)
-Pretty good amount of heat on top of the condenser unit

What I have done so far:
-When the fan/condenser unit was in its 'buzzing' or 'humming' state, I grabbed a screw driver and attempted to 'jump-start' the fan.
Result: Loud evil almost grinding sound. It scared the crap out of me, so I did not attempt this any further. Ran upstairs and shut the AC off from the thermostat.
Perhaps I did not spin it hard enough to fully 'kick it on' all way? It was a light attempt.

-Removed the door to the capacitor from the unit to check for oil leakage or swelling.
There was no swelling or leakage that I could see. The pictures I have seen on the web show an exploded soda can look.
Do capacitors go bad without showing these kinds of symptoms?

I am by NO means a handy man, or any kind of HVAC specialist. I am computer guy who takes his car to jiffy lube. However, I enjoy learning, and would be interested in what you guys think?

From what I gathered, the 'humming' is in most cases, a blown/bad capacitor. And I'm hoping for that, as its such a simple and cheap fix. I even contemplated doing it myself, but fear improperly discharging the capacitor, and shocking myself.

I have called a recommended HVAC guy, and left him a message. I'm hoping he calls back soon, as its going to be a hot day (94). However, its also a holiday weekend.

Key items to keep in mind when responding to this: (1) humming noise for compressor unit. (2) fan has randomly kicked on, then powered off (possibly to overheat). (3) even when fan has kicked on randomly, the air from vents was still warm.

Thanks in advance for any insight.
Old 09-03-10, 10:00 AM
Join Date: Aug 2008
Location: Texas, California
Posts: 1,424
Upvotes: 0
Received 8 Upvotes on 8 Posts
Sounds like a capacitor problem. You can save some money to replace it yourself. Capacitors can go bad without any sign. If you want to learn how to do it, go to You-tube and watch some capacitor replacement videos first..

Thread Tools
Search this Thread
Ask a Question
Question Title:
Your question will be posted in: